The purpose of this study is to provide objective longitudinal cephalometric and polysomnographic data on the effects of orthognathic surgery upon breathing patterns, sleep patterns, radiographic airway measurements, and the incidence of obstructive sleep apnea syndrome. Group I will include five adult patients with obstructive sleep apnea syndrome and mandibular retrognathia who will have been treatment planned for a mandibular advancement procedure. Group II will include five adult patients from the graduate orthodontic clinic at the Ohio State University who will have been treatment planned for a maxillary and/or mandibular setback procedure. Each patient will have polysomnography evaluation at the following times: t1= six weeks prior to surgery, t2= immediately before surgery, t3= six weeks after surgery, and t4= one year after surgery. Polysomnographic evaluation will include determination of airflow, respiratory effort, cardiac activity, blood oxygen desaturation, sleep staging and determination of the apnea and hypopnea index. Lateral cephalometric radiographs will be taken at each of these times and measurements of the posterior airway space and soft tissues of the airway will be made. The proposed study is designed to serve as a preliminary report to determine if the indices of respiration are altered and to what degree after surgery. It will also examine the radiographic airway changes after surgery. This information will aid in predicting the expected amount of change in these variables which will be necessary in determining a sample size for a broader investigation.